This study argues that the ocean has determined the constitution of British identity - both the collective identity of an imperial nation and the private identity of individual imagination. Romantic-era literary works, maritime and seascape paintings, engravings and popular texts reveal a problematic national and individual engagement with the sea. Historians have long understood the importance of the sea to the development of the British empire, yet literary critics have been slow to take up the study of oceanic discourse, especially in relation to the Romantic period. Scholars have historicized "Nature" in literature and visual art as the product of an aesthetic ideology of landscape and terrestrial phenomena; my intervention is to consider ocean-space and the sea voyage as topoi that actively disrupt a corresponding aesthetic of the sea, rendering instead an ideologically unstable oceanic imaginary. More than the "other" or opposite of land, in this reading the sea becomes an antagonist of Nature. When Romantic poets looked to the ocean, the tracks of countless voyages had already inscribed an historic national space of commerce, power and violence. However necessary, the threat presented by a population of seafarers whose loyalty was historically ambiguous mapped onto both the material and moral landscape of Britain. I argue that the British Ocean as a phenomenally fluid space defined by the circulation of trade destabilizes ideological projections of the nation into the sea.